1. Field of the Invention
This invention relates to the field of solenoids having a core or armature plunger and means for latching the plunger in its energized position so that the plunger will remain there when the solenoid is de-energized, and, more particularly, to an improved solenoid assembly wherein the plunger is both latched and unlatched by application of current pulses and in which the latching mechanism itself is operated by a strictly mechanical, non-magnetic means.
2. Description of the Prior Art
Core-plunger solenoids of the latching type are broadly well-known. More specifically, it is generally known to provide a means for latching a core-plunger in its energized or retracted position so that the plunger will remain in that position when the solenoid is de-energized. Various means are then provided for unlatching the plunger upon the next energization of the solenoid so that the plunger can be returned to its unenergized or unretracted position. However, such prior art latching mechanisms either include a magnetizable element controlled by the magnetic field, two oppositely-wound solenoid coils which must be energized in sequence to perform the latching and unlatching functions, means for energizing the solenoid with successive current pulses of opposite polarities to perform the latching and unlatching functions, plungers having two separate plunger sections which are separated by a spring, or latch means external to the plunger itself for latching switch contacts and wherein the plunger returns to its unretracted position upon each de-energization of the solenoid. Such prior art devices are disclosed, for example, in the following U.S. Pat. Nos. 2,340,092, 2,448,959, 2,515,258, 2,515,259, 2,885,606, 3,290,631, 3,307,131, 3,689,857, 3,735,296, 3,895,331, 3,983,520 and 4,078,709.